Prophylactic antidepressants may not only prevent overt depression but may also diminish the development of sub-clinical depressed mood. Effective prevention of a broad range of neuropsychiatric symptoms by use of citalopram has the potential to diminish morbidity associated with PEG-IFN treatment and consequently allow a greater number of patients to complete full therapy. In addition, such an approach may help patients remain adherent to their HIV therapy during the course of HCV treatment which could have long-term personal and public health implications by preventing the emergence of HIV resistance. Furthermore, if shown to be an effective strategy for preventing neuropsychiatric symptoms, treatment for HCV may become more accessible to the large number of patients who may not have ready access to the frequent and intensive psychiatric monitoring, necessary for the early detection and treatment of depression that manifests on PEG-IFN.